In Judd Apatow’s riotous Knocked Up, the marrieds, Pete (Paul Rudd) and Debbie (Leslie Mann), represented what awaited Katherine Heigl and Seth Rogen’s characters as they contemplated the leap into parenthood. Making the grass on the other side look fairly parched, both actors did deft, memorable work, particularly Mann; her whiny-but-self-aware mother of two was the kind of droll character you wanted more of.

Five years later, here Mann is again as Debbie in This Is 40, a movie writer-director Apatow has described as the “sort-of” sequel to Knocked Up and some wags on Twitter have described, rightly, as This is 40 Minutes Too Long. (It is 2 hours and 14 minutes.) This comic tale of marital doldrums is a demonstration of Apatow’s signature generosity as a director: he loves actors, he loves improvisation, he loves being on set. Maybe too much. This Is 40 doesn’t go on quite the narrative walkabout his Funny People did, but it needed a savage edit.

Yet it starts strong: on the morning of her 40th birthday, Debbie perches at the window of her bedroom, wearing rubber gloves and a towel over her hair, sneaking a cigarette, swabbing herself with baby wipes and gobbling gum afterward. The middle-aged woman hiding her vice rang so terrifically true it made me laugh aloud. As Apatow introduces his themes (sagging body parts and sex lives as both Debbie and Pete turn 40 in the same week, financial trouble, is-this-all-there-is woes) there are similar sharp observations about modern life—although it must be said, a very white, upper middle class life.

Subplots are everywhere, but go nowhere in particular. Between Pete and Debbie’s two workplaces (his record company, her high-end boutique) and their fathers (Albert Brooks and John Lithgow, respectively), This Is 40 is stuffed with supporting players. Brooks is mooching off Pete and Debbie in order to support his IVF-engineered triplet toddlers, who he can’t tell apart. Lithgow visits so rarely he doesn’t recognize his own grandchildren. Pete is trying to make the amiable ’80s rock star Graham Parker (who is 62) hot again (even his employees, played by Chris O’Dowd and Lena Dunham, consider this hopeless). Debbie is trying to figure out which of her two employees (Megan Fox and Charlyne Yi, reprising her Knocked Up role) is stealing from the till.

Pete and Debbie’s daughters, Sadie (13) and Charlotte (8), are played by the same young actresses who had the roles in Knocked Up, Judd and Leslie’s daughters, Maude and Iris Apatow. Maude succeeds in projecting some of the gloomy edge of a real teenager, while Iris, bless her, performs in much the same way most of your friends’ sweeter children do when called upon to show off their talents, which is to say dutifully, with an eye on the exit or perhaps, the far more entertaining American Girl doll waiting in the next room. On matters such as parent-child relationships, schools and pop culture, Apatow’s writing is briskly on-target and quite funny. I’ll chuckle every time I think of one of the movie’s best sight gags, the grey-haired pregnant lady walking through Sadie and Charlotte’s school, looking at least 55. Same for the bit about Lost. Sadie uses various electronic devices throughout the movie to watch episodes of the show, which she’s seeing for the first time, and Pete mocks her obsession with it. “I don’t make fun of your Mad Men!” she retorts. Which, she adds, sucks. From the shots he’s chosen to highlight from Lost, Locke at a typically tense, dramatic moment, Jack lying on the beach having his epiphany in the last episode, it’s seems Apatow gets the allure of Lost—I bet in real life he and Maude watched it together—but can step outside it to acknowledge the show’s inherent silliness in retrospect.

What he isn’t able to do, presumably because it’s just too personal, is step outside the allure of this narrative and see what is inherently silly about Pete and Debbie’s “crisis” and how it drags down the narrative. As the movie goes on, the laughs are fewer and farther between, and for the last 30 minutes, not only did I not laugh, I wanted it to end so I could get back to my own boring but less precious life. The movie lacks any urgency—there’s no way Pete and Debbie will ever break up. They fret about not liking other, but there’s never any question that they do; they just like bickering nearly as much as they like each other. We never see a real fight, an ugly, knock-down, drag out marital blow-up. We see artificial, snappy battles that might call to mind the screwball comedies of the ’30s and ’40s, if they weren’t so resolutely cute in a 21st century, self-absorbed kind of way. Pete and Debbie, but particularly Debbie, are so busy adroitly commenting on their own responses and emotions that none of their responses and emotions feel genuine.

And the material starts to contradict itself. At about the midway point, Pete and Debbie go away for a blissful naughty weekend in Laguna. They swim, drink, enjoy a medicinal marijuana cookie, order room service and to the best of my recollection, have sex. (Mann and Rudd have no sexual spark. When Melissa McCarthy, in a small, funny part as a contentious parent from the girl’s school, accuses them of looking “like they’re in a bank commercial,” she’s right; they’re that bland together.) In Laguna they discuss their mutual love; it’s gushy and happy. Then a few scenes later, during an interminable party sequence, Pete tells Debbie. “It’s not your fault you can’t feel love.” Huh? What about Laguna, honey? What about earlier compliments to her awesome, loving mothering, which requires she feel love? Within 15 minutes, they’ve decided they’ll be fine, waving off all the problems we were supposed to care about.

In contrast, Knocked Up, though it also ended with unrealistic softness, seems like the height of focus and narrative drive. Speaking of: Given how bloated the second half of the movie is—it has middle-age spread—couldn’t Apatow have thrown Knocked Up fans a bone and at least mentioned Alison (Heigl) and Ben (Rogen)? Ben’s buddy Jason (Jason Segel), now Debbie’s personal trainer, comes to the big birthday party scene. Debbie’s distant surgeon father (John Lithgow) participates in a discussion of his lousy parenting, but Debbie’s sister never comes up. No one says, hey, where is Alison and that dope she married? Heigl did some post Knocked Up dissing, calling the film “a little sexist,” but does that mean she’s so dead to Apatow that Alison’s name can’t even come up in normal conversation? Or maybe, she and Debbie had a fight about who was more self-absorbed. That I could see.

Mary Pols has been reviewing film and occasionally books for TIME since 2009. She has degrees from Duke University, where she studied art history, and the University of California Berkeley’s School of Journalism. She is the author of a memoir about untraditional parenthood. It was made into a short-lived television comedy where everything turned out traditionally.

Accidentally on Purpose: The True Tale of a Happy Single Mother is available for nearly nothing at various online bookstores and from boxes in Pols' barn.